Otosclerosis
Alan L. Cowan, MDTomoko Makishima, MD, PhD
Department of OtolaryngologyUniversity of Texas Medical BranchGalveston, TX
October 18, 2006
IntroductionOtosclerosis Primary metabolic bone disease of the otic capsule and ossiclesResults in fixation of the ossicles and conductive hearing lossMay have sensorineural component if the cochlea is involvedGenetically mediatedAutosomal dominant with incomplete penetrance (40%) and variable expressivity
History of Otosclerosis and Stapes Surgery1704 Valsalva first described stapes fixation1857 Toynbee linked stapes fixation to hearing loss1890 Katz was first to find microscopic evidence of otosclerosis1893 Politzer described the clinical entity of otosclerosis1890 Bacon describes medical therapy for the condition, and supports the common view that surgery should not be considered for a moment.
History of Otosclerosis and Stapes SurgeryGunnar Holmgren (1923)Father of fenestration surgerySingle stage technique
SourdilleHolmgrens student3 stage procedure64% satisfactory results
History of Otosclerosis and Stapes SurgeryJulius LempertPopularized the single staged fenestration procedure
John HouseFurther refined the procedurePopularized blue lining the horizontal canal
History of Otosclerosis and Stapes Surgery
Fenestration procedure for otosclerosisFenestration in the horizontal canal with a tissue graft covering>2% profound SNHLRarely complete closure of the ABGMay exhibit vestibular disturbances
History of Otosclerosis and Stapes SurgerySamuel Rosen1953 first suggest mobilization of the stapesImmediate improved hearingRe-fixation
History of Otosclerosis and Stapes SurgeryJohn Shea1956 first to perform stapedectomyOval window vein graftNylon prosthesis from incus to oval window
Epidemiology
10% overall prevalence of histologic otosclerosis1% overall prevalence of clinically significant otosclerosis
Epidemiology Race Incidence of otosclerosisCaucasian10%Asian5%African American1%Native American0%
EpidemiologyGender Histologic otosclerosis 1:1 ratio Clinical otosclerosis 2:1 (W:M)Possible progression during pregnancy (10%-17%)Studies which have demonstrated changes during pregnancy are often retrospective or lack audiometric data.Studies comparing multigravid vs. nulligravid women with otosclerosis have failed to show audiometric differences. Bilaterality more common (89% vs. 65%)
Pathophysiology
Osseous dyscrasiaResorption and formation of new boneLimited to the temporal bone and ossiclesInciting event unknownHereditary, endocrine, metabolic, infectious, vascular, autoimmune, hormonal
PathologyTwo phases of diseaseActive (otospongiosis phase)Osteocytes, histiocytes, osteoblastsActive resorption of boneDilation of vesselsSchwartzes signMature (sclerotic phase)Deposition of new bone (sclerotic and less dense than normal bone)
Pathology
Most common sites of involvementFissula ante fenestrumRound window niche (30%-50% of cases)Anterior wall of the IAC
Non-clinical foci of otosclerosis
Anterior footplate involvement
Annular ligament involvement
Bipolar involvement of the footplate
Round Window
Labyrinthine Otosclerosis1912 Siebenmann described labyrinthine otosclerosisSuggested otosclerosis may cause SNHL viaToxic metabolitesDecreased blood supplyDirect extensionDisruption of membranes
Hyalinization of the spiral ligament
Erosion into inner ear
Organ of Corti
Cochlear OtosclerosisAudiometric studiesSome studies have shown that in cases of unilateral otosclerosis ~ 60% may have decreased sensory thresholds even after stapes surgery
Histiologic studiesCases of documented otosclerosis and a large sensory loss have shown large foci of otosclerosis in the otic capsule.Many cases of large otic capsule foci without sensory loss or of sensory loss without foci have also been described.
Biochemical studiesSome authors have noted increased levels of perilymph protein during stapedotomy in patients with radiographic evidence of otic capsule foci and sensory hearing loss.
ConclusionMany experts believe that extensive involvement of the cochlea will produce sensorineural hearing deficits, although it is not known how this occurs or why it only occurs in a subset of patients with cochlear foci.
Diagnosis of Otosclerosis
HistoryMost common presentationWomen age 20 - 30Conductive or Mixed hearing lossSlowly progressive, Bilateral (80%)Asymmetric Tinnitus (75%)
HistoryAge of onset of hearing lossProgressionLateralityAssociated symptomsDizzinessOtalgiaOtorrheaTinnitus
HistoryFamily history2/3 have a significant family historyParticularly helpful in patients with severe or profound mixed hearing lossPrior otologic surgeryHistory of ear infectionsVestibular symptoms25%Most commonly dysequilibriumOccasionally attacks of vertigo with rotatory nystagmus
Physical ExamOtomicroscopyMost helpful in ruling out other disordersMiddle ear effusionsTympanosclerosisTympanic membrane perforationsCholesteatoma or retraction pocketsSuperior semicircular canal dehiscenceSchwartzes signRed hue in oval window niche area10% of casesPneumatic otoscopyDistinguish from malleus fixation
Physical ExamTuning forksHearing loss progresses form low frequencies to high frequencies256, 512, and 1024 Hz TF should be usedRinne256 Hz negative test indicates at least a 20 dB ABG512 Hz negative test indicates at least a 25 dB ABG
Differential DiagnosisOssicular discontinuityCongenital stapes fixationMalleus head fixationPagets diseaseOsteogenesis imperfectaSuperior semicircular canal dehiscence
AudiometryTympanometryImpedance testingAcoustic reflexesPure tones
TympanometryJerger (1970) classification of tympanogramsType AType AType AsType AdType BType C
Acoustic ReflexesResult from a change in the middle ear compliance in response to a sound stimulusChange in compliance Stapedius muscle contractionStiffening of the ossicular chainReduces the sound transmission to the vestibule
Acoustic ReflexesOtosclerosis has a predictable pattern of abnormal reflexes over timeReduced reflex amplitudeElevation of ipsilateral thresholdsElevation of contralateral thresholdsAbsence of reflexes
Pure Tone AudiometryMost useful audiometric test for otosclerosisCharacterizes the severity of diseaseFrequency specific
Carharts notchHallmark audiologic sign of otosclerosisDecrease in bone conduction thresholds5 dB at 500 Hz10 dB at 1000 Hz15 dB at 2000 Hz5 dB at 4000 Hz
Pure Tone AudiometryLow frequencies affected firstBelow 1000 Hz
Rising air lineStiffness tilt Secondary to stapes fixation
With disease progressionAir line flattens
Pure Tone AudiometryCarharts notchProposed theoryStapes fixation disrupts the normal ossicular resonance (2000 Hz)Normal compressional mode of bone conduction is disturbed because of relative perilymph immobilityMechanical artifactReverses with stapes mobilization
Pure Tone AudiometryCommittee on Hearing and BalanceSet standards for reporting results in cases of otosclerosis procedures.Operative hearing results should be reported using post-operative data, specifically, the post-operative air-bone gap.This prevents exaggeration of surgical results and overclosure. Adopted by the AAOHNS in 1994Important in reviewing literature regarding surgical outcomesStudies prior to this time often use pre-op bone lines and post-op air conduction measurements which may exaggerate results.This convention is not uniform in all parts of the world, so the methods is very important in determining the consistency of data.
ImagingComputed tomography (CT) of the temporal boneProponents of CT for evaluation of otosclerosisPre-opCharacterize the extent of otosclerosisSevere or profound mixed hearing lossEvaluate for enlarge cochlear aqueductPost-opRecurrent CHLRe-obliteration vs. prosthesis dislocationVertigo
Halo sign
Pagets disease
Osteogenesis Imperfecta
Management OptionsMedical AmplificationSurgeryCombinations
Patient SelectionFactorsResult of tuning fork tests and audiometrySkill of the surgeonFacilitiesMedical condition of the patientPatient wishes
SurgeryBest surgical candidatePreviously un-operated earGood healthUnacceptable ABG25 to 40 dBNegative Rinne testExcellent discriminationDesire for surgery
SurgeryOther factorsAge of the patientElderlyPoorer results in the high frequenciesCongenital stapes fixation (44% success rate)Juvenile otosclerosis (82% success rate)OccupationDiverPilotAirline steward/stewardess
SurgeryOther factorsVestibular symptomsMeniere's diseaseConcomitant otologic diseaseCholesteatomaTympanic membrane perforation
Surgical StepsSubtleties of technique and styleLocal vs. general anesthesiaStapedectomy vs. partial stapedectomy vs. stapedotomyLaser vs. drill vs. cold instrumentationOval window sealsProsthesis
Canal Injection2-3 cc of 1% lidocaine with 1:50,000 or 1:100,000 epinephrine
4 quadrants
Bony cartilaginous junction
Raise Tympanomeatal Flap6 and 12 oclock positions
6-8 mm lateral to the annulus
Take into account curettage of the scutum
Separation of chorda tympani nerve from malleusSeparate the chorda from the medial surface of the malleus to gain slack
Avoid stretching the nerve
Cut the nerve rather than stretch it
Curettage of ScutumCurettage a trough lateral to the scutum, thinning it
Then remove the scutum (incus to the round window)
Curettage of ScutumExposure Vertical:Facial nerve to round windowHorizontal:Pyramidal process to malleus
Preservation of bone over incus
Middle ear examinationMobility of ossiclesConfirm stapes fixationEvaluate for malleus or incus fixation
Abnormal anatomyDehiscent facial nerveOverhanging facial nerveDeep narrow oval window nicheOssicular abnormalities
Measurement for prosthesisMeasurementLateral aspect of the long process of the incus to the footplate
Total StapedectomyUsesExtensive fixation of the footplateFloating footplateDisadvantagesIncreased post-op vestibular symptomsMore technically difficultIncreased potential for prosthesis migration
Stapedotomy/Small FenestraOriginally for obliterated or solid footplatesEurope1970-80
First laser stapedotomy performed by Perkins in 1978Less trauma to the vestibuleLess incidence of prosthesis migrationLess fixation of prosthesis by scar tissue
Drill Fenestration0.7mm diamond burrMotion of the burr removes bone dustAvoids smoke productionAvoids surrounding heat production
Laser FenestrationLaserAvoids manipulation of the footplateArgon and Potassium titanyl phosphate (KTP/532)Wave length 500 nmVisible lightAbsorbed by hemoglobin Surgical and aiming beamCarbon dioxide (CO2)10,000 nmNot in visible light rangeSurgical beam onlyRequires separate laser for an aiming beam (red helium-neon)Ill defined fuzzy beam
Oval window sealTragal perichondriumVein (hand or wrist)Temporalis fasciaBloodFatGelfoam (now discouraged)
Reconstructing the annular ligament
Placement of the ProsthesisProsthesis is chosen and length pickedSome prefer bucket handle to incorporate the lenticular process of the incus
Stapedectomy vs. StapedotomyABG closure < 10dB (PTA)
Special Considerations and Complications in Stapes Surgery
Overhanging Facial NerveUsually dehiscentConsider aborting the procedureFacial nerve displacement (Perkins, 2001)Facial nerve is compressed superiorly with No. 24 suction (5 second periods)10-15 sec delay between compressionsPerkins describes laser stapedotomy while nerve is compressedWire piston usedAdd 0.5 to 0.75 mm to accommodate curve around the nerve
Floating FootplateFootplate dislodges from the surrounding OW nicheIncidental findingMore commonly iatrogenicPreventionLaserFootplate control holeManagementAbortH. House favors promontory fenestration and total stapedectomyPerkins favors laser fenestration
Diffuse Obliterative OtosclerosisOccurs when the footplate, annular ligament, and oval window niche are involved Closure of air-bone gap < 10 dB less common.Refixation commonly occurs
Perilymphatic GusherAssociated with patent cochlear aqueductMore common on the leftIncreased incidence with congenital stapes fixationIncreases risk of SNHLManagementRough up the footplateRapid placement of the OW seal then the prosthesisHOB elevated, stool softeners, bed rest, avoid Valsalva, +/- lumbar drain
Round Window Closure20%-50% of cases1% completely closed
No effect on hearing unless 100% closed
Opening has a high rate of SNHL
SNHL1%-3% incidence of profound permanent SNHLSurgeon experienceExtent of diseaseCochlearPrior stapes surgeryTemporarySerous labyrinthitisReparative granulomaPermanentSuppurative labyrinthitisExtensive drillingBasilar membrane breaksVascular compromiseSudden drop in perilymph pressure
Reparative GranulomaGranuloma formation around the prosthesis and incus2 -3 weeks postopInitial good hearing results followed by an increase in the high frequency bone line thresholdsAssociated tinnitus and vertigoExam reddish discoloration of the posterior TMTreatmentME explorationRemoval of granulomaPrognosis return of hearing with early excisionAssociated with use of Gelfoam
VertigoMost commonly short lived (2-3 days)More prolonged after stapedectomy compared to stapedotomyDue to serous labyrinthitisMedialization of the prosthesis into the vestibuleWith or without perilymphatic fistulaReparative granuloma
Recurrent Conductive Hearing LossSlippage or displacement of the prosthesisMost common cause of failureImmediateTechniqueTrauma DelayedSlippage from incus narrowing or erosionAdherence to edge of OW nicheStapes re-fixationProgression of disease with re-obliteration of OWMalleus or incus ankylosis
AmplificationExcellent alternative Non-surgical candidatesPatients who do not desire surgery
Patient satisfaction rate lower than that of successful surgeryCanal occlusion effectAmplification not used at night
MedicalSodium Fluoride1923 - Escot suggested using calcium fluoride1965 Shambaugh popularized its useMechanismFluoride ion replaces hydroxyl group in bone forming fluorapatiteResistant to resorptionIncreases calcification of new boneCauses maturation of active foci of otosclerosis
MedicalSodium FluorideReduces tinnitus, reverses Schwartzes sign, resolution of otospongiosis seen on CT OTC FloricalDose 20-120mgIndicationsNon-surgical candidatesPatients who do not want surgerySurgical candidates with + Schwartzes signTreat for 6 mo pre-op Postop if otospongiosis detected intra-op
MedicalSodium fluorideHearing results50% stabilize30% improveRe-evaluate q 2 yrs with CT and for Schwartzes sign to resolveIf fluoride are stopped expect re-activation within 2-3 years
MedicalBisphosphonatesClass of medications that inhibits bone resorption by inhibiting osteoclastic activityDosing not standardOften supplement with Vitamin D and CalciumStudies conducted on otosclerosis patients with neurotologic symptoms report the majority of patients with subjective improvement or resolution.Future application of this treatment unclear, especially with new reports of bisphosphonate related osteonecrosis.
ReferencesBacon, Gorham. A Manual of Otology. Lea Brothers & Co. New York, NY. 1898.Banerjee A, Whyte A, Atlas. Superior canal dehiscence: review of a new condition. Clinical Otolaryngology. 30, 9-15.Brooker KH, Tanyeri H. Etidronate for the Neurotologic Symptoms of Otosclerosis: Preliminary Study. Ear, Nose & Throat Journal. June 1997; 76 (6): p371-377.Causse JR et al. Sodium fluoride therapy. Am J Otol 1993;14(5):482-490Committee on Hearing and Equilibrium. Committee on Hearing and Equilibrium guidelines for the evaluation of results of treatment of conductive hearing loss. Otolaryngology Head and Neck Surgery. 113 (3) pp. 186-7.Glasscock II ME, et al. Twenty-five years of experience with stapedectomy. Laryngoscope 1995;105:899-904House HP, Kwartler JA. Total stapedectomy. Otologic Surgery, 2nd ed. edited by Brackmann, Shelton, and Arriaga, W.B. Saunders 2001;226-234Hough J. Partial stapedectomy. Ann Otol Rhinol Laryngol 1960;69:571House J. Otosclerosis. Otolaryngol Clinics 1993;26(3):323-502Jerger J. Clinical experience with impedance audiometry. Arch Otolaryngol 1970;92:311Lempert J. Improvement in hearing in cases of otosclerosis: A new, one stage surgical technique. Arch Otolaryngol 1938;28:42-97Lippy WH, Schuring AG. Treatment of the inadvertently mobilized footplate. Otolaryngol Head Neck Surg 1973;98:80-81Meyer S. The effect of stapes surgery on high frequency hearing in patients with otosclerosis Am J Otol 1999;20:36-40Millman B. Giddings, NA and Cole, JM. Long-term follow-up stapedectomy in children and adolescents. Otol Head Neck Surg 1996;115(1):78-81Minor L. Clinical Manifestiations of Superior Semicircular Canal Dehiscence. The Laryngoscope. 2005. 115: 1717-1727.Muller, C. Gadre, A. Otosclerosis. Quinns online textbook of Otolaryngology. http://www.utmb.edu/otoref/Grnds/GrndsIndex.html.Nelson EG, Hinojosa R. Questioning the Relationship between Cochlear Otosclerosis and Sensorineural Hearing Loss: A Quantitative Evaluation of Cochlear Structures in Cases of Otosclerosis and Review of the Literature. The Laryngoscope. 2004; 114: 1214-1230Perkins RC. Laser stapedotomy. Otologic Surgery, 2nd ed. edited by Brackmann, Shelton, and Arriaga, W.B Saunders 2001;245-260Perkins RC. Laser stapedotomy for otosclerosis. Laryngoscope 1980;91:228-241Politzer. Primary Diseases of the Bony Labyrinthine Capsule. Archives of Otology, 1894, vol. xxiii. P. 255.Roland PS. Otosclerosis. www.emedicine.com/ped/topic1692.htm. 2002;1-11Roland PS, Meyerhoff WL. Otosclerosis. Otolaryngology-Head and Neck Surgery. 3rd ed., edited by Byron J. Bailey, Lippincott Williams & Wilkins, Philadelphia 2001;1829-1841Rosen S. Restoration of hearing in otosclerosis by mobilization of the fixed stapedial footplate. An analysis of results. Laryngoscope 1955;65:224-269Shea J Jr. Fenestration of the oval window. Ann Otol Rhinol Laryngol 1958;67:932-951Shambaugh G. Clinical diagnosis of cochlear (labyrinthine) otosclerosis. Laryngoscope 1965;75:1558-1562Shambaugh GE, Jr. and Glasscock ME, III. Surgery of the ear, 3rd ed. Philadelphia, W. B. Saunders, 1980;455-516Toynbee, Joseph. The Diseases of the Ear: Their Nature, Diagnosis, and Treatment. With a Supplement by James Hinton. London, 1868.